1. Field of the Invention
The present invention relates generally to a heat sink, and more particularly to a heat sink for a radiographic sensor device.
2. Description of the Background Art
Radiographic imaging is the detection of radiation in order to form an image. By detecting the amount of radiation emanating from a test subject, the resultant image may give a representative view of the structure of the test subject.
Radiographic imaging typically employs gamma rays. Gamma rays are a form of radiation that is emitted by excited atomic nuclei during the process of passing to a lower excitation state. Gamma radiation is capable of passing through soft tissue and bone. Gamma radiation may be provided by a radiopharmaceutical, such as thallium or technetium, for example, that is administered to the patient. The radiopharmaceutical travels through the patient""s body, and may be chosen to be absorbed or retained by an organ of interest. The radiopharmaceutical generates a predictable emission of gamma rays through the patient""s body that can be detected and used to create an image.
A radiographic imaging device may be used to detect radiation emanating from the patient and may be used to form an image or images for viewing and diagnosis. The radiographic imaging device may be a device such as a gamma or gamma ray camera, also referred to as a scintillation camera or an Anger camera. The radiographic imaging device allows a doctor to perform a diagnosis on a patient in a non-invasive manner and additionally may allow the doctor to observe organ function. In addition, the radiographic imaging device may be used for other imaging functions.
A radiographic imaging device typically contains one or more radiographic sensor devices, such as a solid state detector. The detector may be a module made of cadmium zinc telluride (CZT) that generates an electrical signal representative of the location of gamma ray interaction in the detector material. The accumulated counts at each stored location (as stored in a memory device) may be used to create an image of the distributed radiation field of interest.
A number of radiographic sensor devices may be tiled in an array to form a detector head. The detector head may be formed such that the radiographic sensor devices are individually detachable for maintenance, adjustment, etc.
Sensor heating may occur in a radiographic sensor device, caused by heat generated during operation. This leads to several problems in a radiographic sensor device. The heat may degrade the sensor efficiency. A sensor at elevated temperatures is not as sensitive and is less able to detect extreme high or low levels of radiation from the subject. In addition, sensor heating may cause mechanical defects, such as warping or expansion and contraction of the sensor material, with resulting cracking or other mechanical failures.
In the prior art, cooling of the sensor may be achieved by using a cooling fluid. However, such cooling systems are complicated, expensive, and prone to failure. It is more common in the prior art to use a simple heat sink. Heat sinks are known in the art and are commonly used for solid state electronic components, such as processors, etc., and are mechanically simple and inexpensive. The conventional heat sink is typically fabricated of a metal possessing a high thermal conductivity. The conventional heat sink is generally rectangular in shape and physically contacts the device to be cooled, and may include cooling fins or protrusions that dissipate the heat into the surrounding air. This generally requires a large and continuous contact area between the heat producing device and the heat sink.
Although the prior art heat sink is acceptable for purely electronic devices, a conventional heat sink may be difficult to fit into a radiographic imaging device. For a radiographic detector head, the contact area available to the heat sink is necessarily limited. In addition, a heat sink in the prior art may not be designed to pass through an intervening circuit board, such as a PC board mating with a radiographic sensor device. Furthermore, a heat sink according to the prior art does not help to position the radiographic sensor device with respect to other sensor devices in a multi-device array, such that each sensor device is in the same plane.
Therefore, there remains a need for an improved heat sink for a radiographic imaging device.
A heat sink system for a radiographic sensor device is provided according to a first embodiment of the invention. The heat sink system comprises a heat sink formed of a first material possessing a first predetermined thermal conductivity. The heat sink system further comprises a thermal channel device formed of a second material possessing a second predetermined thermal conductivity. The thermal channel device comprises at least one contact portion adapted to contact the radiographic sensor device and an extending member that extends away from the at least one contact portion and contacts the heat sink. The thermal channel device is designed to extend between and substantially contact the heat sink and the radiographic sensor device when the heat sink system is assembled. The thermal channel device conducts heat from the radiographic sensor device to the heat sink.
A heat sink system for a radiographic sensor device is provided according to a second embodiment of the invention. The heat sink system comprises a heat sink formed of a first material possessing a first predetermined thermal conductivity. The heat sink system further comprises a thermal channel device formed of a second material possessing a second predetermined thermal conductivity. The thermal channel device is adapted to extend through a thermal channel aperture in an intervening circuit board positioned between the heat sink and the radiographic sensor device. The intervening circuit board is held in a spaced-apart relation from both the heat sink and the radiographic sensor device by the thermal channel device. The thermal channel device comprises at least one contact portion adapted to contact the radiographic sensor device and a substantially cylindrical extending member that extends away from the at least one contact portion and contacts the heat sink. The substantially cylindrical extending member includes a threaded outer surface portion adapted to receive a threaded fastener capable of removably affixing the thermal channel device to the intervening circuit board. The substantially cylindrical extending member further includes a threaded fastener aperture adapted to receive a threaded elongate fastener capable of removably affixing the thermal channel device to the heat sink. The thermal channel device is designed to extend through the intervening circuit board and to extend between and substantially contact the heat sink and the radiographic sensor device when the heat sink system is assembled. The thermal channel device conducts heat from the radiographic sensor device to the heat sink.
A method of conducting heat away from a radiographic sensor device is provided according to an embodiment of the invention. The method comprises the step of providing a heat sink formed of a first material possessing a first predetermined thermal conductivity. The method further comprises the step of providing a thermal channel device formed of a second material possessing a second predetermined thermal conductivity. The thermal channel device comprises at least one contact portion adapted to contact the radiographic sensor and an extending member that extends away from the at least one contact portion. The method further comprises the step of contacting the thermal channel device to the heat sink and to the radiographic sensor device. The thermal channel device conducts heat from the radiographic sensor device to the heat sink. The thermal channel device maintains the radiographic sensor device in a substantially parallel spaced-apart relation with the heat sink.
The above and other features and advantages of the present invention will be further understood from the following description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings.